Amplitude limiting device



Jan. 17, 1939., F. STRECKER AMPLITUDE LIMITING DEVICE Filed Sept. 5, 1936 4 E our/ 07 INVENTQR v ZTRECKER FELIX I ATTORNEY UNITED STATES PATENT OFFICE 2,144,036 AMPLITUDE LIMI TINGrDEVICE Felix Strecker, Berlin-Siemensstadt, Germany,

assignor to Siemens & Halske Aktiengesellschaft, Berlin- Siemensstadt, Germany Application September 5, 1936, Serial No. 99,680 In Germany September 1'7, 1935 1 Claim. (Cl. 178-44) The present invention relates to a four pole decircuit having the form of a bridged T-member vice having non-linear characteristics such as are and in which the non-linear elements consist of especially required for the purpose of limiting amsymmetrically arranged non-linear resistors.

plitudes. The following efieots are obtained when applying For a better understandingof the invention, the invention to such circuit.

reference is made to the accompanying drawing, The functioning of this circuit is represented in which: in Figures 3 and 4. Herein U represents the Fig. 1 shows a damping curve of a devicein voltage at the input of the combination, the resistwhich the damping decreases as the applied amances R are plotted on the ordinate axis in kiloplltude increases, ohms (k 9) If the differential transformer is an Fig. 2 is a schematic circuit diagram of a bridge ideal one, the circuit represented, acts in the manform of limiting device, ner of a bridge circuit having the resistors 2R1 Figs. 3 and 4 show the damping curves of the and 1/2R2. If the circuit is to be utilized for the arrangement of Fig. 2, the suppression of small amplitudes, a condition Fig. 5 shows the non-linear resistors coupled of equilibrium is to be attained for low voltages, 15 to a bridge circuit by a transformer, so that there must be the relation 2R1=1/2R2. Fig. 6 shows the non-linear resistors of a bridge For larger amplitudes of the voltage U at the circuit shunted by a variable resistor, input potential, deviations will be produced in the Figs. 7a, 8, 10 and 11 show various damping mean resistance-so that the damping of the memcurves obtainable w th devices made acc d to her decreases. In fulfilling this condition there 20 the invention, v will be obtained as previously pointed out, a

Fig. 7 s ws two arrangements made accorddamping curve formed according to Fig. 1. 8 0 the invention connected n S a Now if, in accordance with the invention, the 9 s a c t di a of a fi d form Of non-linear resistors in the series and parallel a p device made according to e v ionbranches are suitably dimensioned such as indi- Amplitudc limiting means for Small d large cated in Fig. 4, the mean resistance for both comamplitlldcs generally have damping a sbinations is different for verylow voltages U. For tics, either continuously increasing or c nt the amplitude U0 however, the mean resistances us v de asin w t the app Wa ampl tud for the fundamental wave will be almost the v 1 ws an example of a damping charactersame. In case of high voltages the differences of 30 i t c o Such limiting device Small p d the resistances assume rapidly very considerable Dlitudes. Begin g W a rather high Value values, so that the damping decreases rapidly. damp b determined by t put p t nt Hence, a maximum of the damping will be the damping curve decreases with an reached at a finite Value of the amplitude which crease in the amplitude. Devices for such amplidifiers from ero,

tilde limitation e already known, and it has In the example shown, as non-linear resistors, also been already P pos o p y for this especially dry rectifiers, such as copper oxide recp four-D016 v s containing non-linear tifiers are to be considered. However, the subject resistors. However, it was found that for many matter of the invention is not limited thereto,

P p the damping c v s atta ab e With since other non-linear resistors such as hot-consuch circuits for amplitude limitation are insufliductors etc. can likewise be used. The non-lincient. ear resistors may be suitably dimensioned for in- In accordance with the invention, a desired vastance by means of transformers such as shown riation of the damping curve is obtained by introin Fig. As indicated in in addition to 5 ducing poles, or maximum values of the damping, the individual non-linear resistors, a parallel reat any input voltage difiering from zero. As a sistor I0 may also be used. For this resistor the result of this measure, a particular blocking efiect variable type may be used in particular. is especially obtained in the undesirable range or By different dimensioning of the circuit, an enranges of applied voltage. By combining such tire series of damping curves can be produced havdamping curves, any desired variation of the ening the maximum values at various voltages. In 50 tire damping curve can be attained. combining several such curves, any desired varia- The invention relates in particular to four-pole tion of the damping can be obtained, such as indidevices containing a bridge circuit or any other cated in Fig. 7. This figure shows two four-pole compensation circuit, for instance a bridged T- devices V1 and V2 dimensioned in accordance with circuit. Fig. 2 shows an example of a limiting the invention and connected in series. If there 56 exists a voltage U at the input of the first of these four-pole devices, then after passing the four-pole device V1 the value of this voltage will be U1. This voltage will now be applied to the four-pole device V2 so that an output voltage U2 of the entire arrangement will be obtained. In the corresponding damping-voltage curves in Fig. 7a, In and 112 are the damping curves of the four-pole devices. In connecting these two fourpoles in series there will be obtained a variation of the damping curve such as schematically indicated by the curve bges. It should be borne in mind that in case of this series connection the sequence of the four-pole devices plays a certain role. It will be seen that the entire damping curve will be a difierent one since a voltage different from the original voltage is applied to the second four-pole device.

By means of such damping curves in which a maximum of the damping is attained at a finite value of the amplitude, a sharp distinction between the amplitudes to be blocked and those which are left to pass, will be obtained. In connection with'the dimensioning, itshould further.- more be considered that the output amplitude at a decrease of the :input voltage also decreases when the damping is constant. 7 From this, it can be concluded that it is not always necessary to provide an especially great weakening of the very small amplitudes.

A damping curve of certain arrangements such as is shown in Fig. 1 presents a relationship between the output potential and the input potential such as is indicated for instance by .curve I of Fig. 8. The dimensioning according to the invention of the non-linear resistors furnishes however, when based upon a damping curve such as obtained in the example of Fig. 7, a variation of the curve as represented by '2 in Fig. 8. While in the curve I there does not exist a distinct threshold value, a region of distinctly low output potential is now obtained by the use of nonlinear resistors entering into a region of great steepness. Hence by means of the invention, a threshold value is produced and a relative steepeningof the dampening increase can be attained.

As previously stated, the invention is not limited to bridged T-circuits but encompasses also all other limiting circuits in which a so-called compensation circuit is present. An example of another limiting circuit is represented in Fig. 9. Herein, the matching resistors R1 and R2 serve for matching the resistance values of the nonlinear resistors G1 and G2 for adefinite amplitude. At this place a damping pole is then obtained with respect to the fundamental wave 1. e. practically a region of maximum damping. Also in this case,

it is possible to vary the damping curves by varying the biasing potentials of the batteries B1 and B2 by varying the resistors R1 and R2, or the surface in the copper oxide rectifiers.

The explanations relating to the example shown in Fig. 4 refer to limiting means intended to reduce small amplitudes. Equivalent reasoning can also be made in connection with the limiting means for large amplitudes. Also in case of the last mentioned limiting means, circuits according to the diagrams presented, such as for instance according to Fig. 2 can be employed. The matching of the resistors 2R1 and 1/2R2 is then carried out in accordance with the large amplitudes so that the greatest difference exists in case of the small amplitudes. Also in this case, the damping curves are made to intersect each other as indicated in Fig. 10. The resistances in case of large amplitudes will then be relatively the same and in case of small amplitudes they are greatly different from each other. In this way, damping curves are obtained corresponding to those in Fig. 7a, in which the dampings increase simply in accordance with the high voltage values.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

Means for damping a wave of variable amplitude comprising a lead, a circuit including two inductors connected in series across the ends of said lead, two oppositely disposed non-linear resistors connected in series across the outer ends of said inductors, and a pair of non-linear resistors oppositely disposed in shunt'relation and connected between said lead and the common terminal of said inductors.

FELIX STRECKER. 

